Method of forming a reinforced fabric by a compressive shrinking operation

ABSTRACT

A FABRIC IS MADE BY MECHANICALLY INTERLOCKING A NONWOVEN FABROUS WEB INTO A SHRINKABLE WOVEN SCRIM AND THEN SHRINKING THE SCRIM BY HEAT AND COMPRESSION TO CONTRACT THE SCRIM ABOUT THE INTERLOCKED NON-WOVEN FIBERS. THE SHRINKING AND SIMULTANEOUS CRIMPING OF THE SCRIM PRODUCES A SOFT AND SOMEWHAT EXTENSIBLE FELT-LIKE FABRIC.

March 16, 1971 F. E. HEINEMANN 3,570,085

METHOD OF FORMING A REINFORCED FABRIC BY A COMPRESSIVI'! SHRINKING OPERATION Filed oct. 15, 196s L13 FIG. I

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United States Patent O 3,570,085 METHOD F FORMING A REINFORCED FABRIC BY A COMPRESSIVE SHRINKING OPERATION Frederick E. Heinemann, Canton, Mass., assignor t0 W. R. Grace & Co., Cambridge, Mass. @outinuation-in-part of abandoned application Ser. No. 401,268, Uct. 2, 1964. This application Oct. 15, 1968, Ser. No. 767,649

Int. Cl. D04h 1/50 ABSTRACT OF THE DISCLOSURE A fabric is made by mechanically interlocking a nonwoven fibrous web into a shrinkable woven scrirn and then shrinking the scrim by heat and compression to contract the scrim about the interlocked non-woven fibers. The shrinking and simultaneous crimping of the scrim produces a soft and somewhat extensible felt-like fabric.

This application is a continuation-in-part of application 401,268, filed Oct. '2, 1964, now abandoned.

This invention is concerned with a reinforced fabric possessing many of the properties of a true felt. As is well known, the manufacture of true felts is a timeconsuming and difficult process. It is also one in which the manufacturer nds his choice of iibers sharply restricted since many fibers will not felt properly. Additionally, many felts do not have good tensile properties and strength, and are poor with respect to dimensional stability and shape retention.

The product of the present process has much of the appearance of a true felt but possesses good tensile properties, strength, dimensional stability and shape retention. Further, the product of the present invention is superior to many conventional felts with respect to chemical, heat, moth and mildew resistance. For this reason it can, in many situations, perform better than true felts. It lends itself well to use as artificial leather base, when impregnation and coating of the product produce a leather-like product.

I have discovered that if a non-woven web of fibers is interlocked with a heat-shrinkable scrim, e.g. by needlelooming the fibers of the non-woven web into the scrim, and then if the needle-loomed fabric is simultaneously not only heat-shrunk but longitudinally compressed as the heat is applied, the scrim not only will shrink and bind the fibers tightly into the mass, but its own strands become crimped, the scrim threads and fibers occupying different planes within the vertical dimension of the sheet.

The length of the sheet shortens as the process continues. The threads of the scrim first shorten to the degree of their heat-shrinking ability, but thereafter the length of the individual threads and fibers in the scrim no longer decreases. However, by contracting the area in which the threads lie, they crimp to occupy a number of planes within the thickness of the sheet.

During this operation, a heavy pressure is maintained against the fabric to keep it flat and unfolded, and produce a smooth, felt-like surface.

One can picture the product, using a corrugated boX board as a rough analogy. The scrim may be thought of as the corrugated member, the non-woven fibers now forming a flat unbroken surface as the outer layers. In the finished product, the scrim completely disappears from view. If the needle-looming has taken place on both sides of the scrim, the fabric has the feel, drape, and appearance of felt. However, the crimping of the scrim eliminates boardiness because it provides what may be deice scribed as hinge points which allow the fabric to bend without creasing or piping Because this is not a felting operation (the fibers are neither boiled nor beaten), the choice of fibers which may be used in the non-woven layers of the new fabric is very wide indeed.

Practically any fiber which can be formed into a nonwoven web by a carding machine or an air-laying device may be utilized as the surface layer. Examples of suitable bers are cotton, wool, rayon, nylon, fibers formed from polyesters, from vinylchloride-acrilonitrile copolymers, from acrylonitrile, from polytetrofluoroethylene, and polypropylene, and from mixtures of such fibers. It is also possible to use glass. The length and the diameter of the fibers is determined by the surface appearance which one Wishes to give the goods. However, the fibers must be long enough to be handleable on the needling or interlocking apparatus, and fine enough to produce a dense surface. Fibers of 1/2 inch or longer and from 0.5-2.5 denier are useful.

The scrim fabric into which the individual non-woven fibers are interlocked must possess the capacity to shrink, and this effect can be brought about most easily by heating, but sometimes by chemical treatment. The common heat shrinkable materials are suitable, particularly those made of polyester, acrylic, nylon, glass, modacrylic, olefin, rayon, etc., fibers.

In order to shrink and at the same time crimp the scrim, the fabric is passed about a heated drum and under a thick rubber belt which runs under considerable tension.

Crimping not only provides hinge points, and produces a product which is far freer from breaking or creasing than is ordinary felt, but the humping up of the individual strands of the scrim compresses and entangles more of the non-woven fibers with the result that even though a fiber may be reasonably well anchored by the shrinking of the scrim and the closing of the needle hole through which the fiber was forced, it is anchored again by its contact or interfolding with the crimps or corrugations in the scrim. The results contrast markedly with an assembly where the scrim is merely heat-shrunk, for then the scrim layer is pulled together under considerable tension with the result that the material is less iiexible and less soft. Further, the crimped material of the invention very desirably possesses a minimum of pinholes resulting from the needling operation.

FIG. 1 is a much-enlarged, idealized cross-section of the material prior to needling and compressive shrinking;

FIG. 2 shows the material of FIG. 1 being needled;

FIG. 3 is a diagrammatic presentation of the step of compressively shrinking the composite fabric;

FIG. 4 is a detail showing the needled, compressively shrunk material of the invention and the crimping effect which the process imparts to the heat-shrunk, reinforcing threads of the scrim.

The amount of needling which the non-woven web and the scrim must undergo is determined by the surface effect which is desired and, to a lesser degree, by the density of the felt which one wishes to produce. The more needling, the more the fibers are interlocked into the scrim, and a smoother surface is secured in the finished product. Generally about 15 passes on a standard needling device are used. The devices and the method of needling non-woven webs are conventional.

lFIG. 1 shows a composite fabric, 10, made up of a layer of a shrinkable woven scrim, 11, sandwiched between two layers of non-woven webs or batts, 12 and 13. In FIG. 2, the fibers of both batts, 12l and 13, are being interlocked by needle-looming through the composite 10 with barbed needle 14.

Compressive shrinking of the needle-loomed composite fabric, 10, of FIG. 2 is accomplished by passage through an apparatus such as is shown in FIG. 3. The needle-loomed fabric is passed between the heated driven drum, 15, an dan endless belt, 16, which has an elastic, contractable surface such as natural rubber. Rolls, 17 and 18, acting as guides for the rubber belt can be adjusted to cause the belt to hug the drum, 15, and compress that portion of the belt in contact with the drum to adjustable degrees.

In compressive shrinking after the manner shown, the fibers of the fabric are distorted by contacting the area in which the fibers lie without decreasing the actual length of the fibers themselves, `while at the same time the surfaces of the fabric are held flat and parallel to each other because of the very substantial pressure which is exerted on the fabric by the rubber belt.

FIG. 4 shows in detail the needled, compressively shrunk interlocked composite of the invention 19 wherein the threads of scrim y11 are crimped.

EXAMPLE 1 Fiber-100% polyester (Dacron) Type-Continuous filaments Denier of yarn-220 No. of yarns per inch-38 X 38 Weight-2.3 oz./sq. yard Finishing-None (not heat set or secured) Weave-Plain On the opposite side of the Daeron scrim, a batt cornposed of rayon fibers (l1/2 denier per fiber, 1%6 inches in length) weighing 4 ounces per square yard was needled into the scrim. The needling was carried out on a James Hunter laboratory needle loom using Torington needles 15 x 18 x 36 x 31/2 CB. Fifteen passes of the fabric were made through the loom in the following manner:

Advance of fabric per Depth of needle peneneedle penetration (in.) tration (in.)

Number passes' The needled fabric was shrunk by passing the fabric through a compressive shrinking device such as is shown in FIG. 3. The temperature of the nip roll was 200 F. and a 31/G-inch compression into the rubber belt was used. Prior to passing the fabric through the device, the fabric was preconditioned by exposing it to an atmosphere of 100% relative humidity at 25 C. for 10 minutes. After two passes through the compressive shrinking device (one pass in the machine direction, and one in the cross direction), the fabric was found to have shrunk in the machine direction and 15% in the cross direction. Before shrinking was accomplished, the fabric weighed 6.84 ounces per square yard, and was 0.081 inch thick. After passage through the shrinking device, the weight of the fabric was 9.2 ounces per square yard, and the thickness was 0.030 inch.

EXAMPLE II A needled fabric was prepared as set forth in Example 1 and passed through a compression shrinking device at a nip roll temperature of 250 F., and :iig-inch compres- SiOn into the rubber belt. The fabric was preconditioned with moisture as described in Example 1, and then was passed four times through the shrinking unit (once on each face of the fabric, and once in each direction of the material). The shrinkage secured by this treatment was 28% of length in the linear direction, and 28% in the cross direction. Before shrinking, the fabric weighed 6.8 ounces per square yard and was 82 mils thick. After shrinkage, the weight of the fabric was 13.3 ounces per square yard, and its thickness was 34 mils.

EXAMPLE III A carded batt of polyester filaments (Daeron), 3 denier per fiber 3 inches in length and weighing one ounce per square yard, was needle-punched on to one face of a polyester scrim as described in Example 1. The opposite face of the scrim was needle-punched with a carded batt of the same fiber except that the batt weighed four ounces per square yard. The needling operation was the same as described in Example 1. After needling, the fabric weighed 7.43 ounces per yard and was 66 mils thick. Compressive shrinkage was carried out following the procedure described in Example l with the fabric being passed one pass in each direction through the shrinking zone. After shrinking, the linear dimensions of the fabric were 15% less in each direction, the weight of the fabric was 8.5 ounces per square yard, and its thickness was 49 mils. This material had the following physical properties:

Machine Cross direction direction Tensile strength, lbs/inch of width-.. 106 8G Elongation at break, percent. 28 21 Slit tear, lbs 17 22 The following table illustrates fabrics within the scope of this invention which were prepared utilizing the scrim and procedure of Example 1 with non-woven webs of the fibers designated below. The non-woven webs were also prepared according to the procedure described in Example l.

Example Number 1 Fiber Ltf1-FMC Corp., American Viscose Division.

1 Fortrel 400 reaction product of ethylene glycol and terephthalic acid Celanese Corp., New York, N .Y.

3 Egyptian cotton waste.

l Nylon 201-E. I. du Pont de Nemours d: Co., Wilmington, Del.

5 Hercules Powder Co., Wilmington, Del.

EXAMPLE IV A portion of material produced by the process of Example 1 was impregnated with a butadiene-styrene latex of approximately 28% solids concentration which contained appropriate Vulcanizing anti-oxidant and stabilizing additives. Impregnation was carried out by submerging the web in the bath of latex and then passing the web under squeeze rolls which permitted of latex solids calculated on the weight of the compressively shrunk fabric to remain. After the impregnated sheet is dried and cured, the thickness will be found to lie between 40 and 44 mils. This material was further finished by a pyroxylin coat and embossed with an artificial leather grain. It was then stretched across a conventionally padded spring-bottom chair seat and subjected to destructive testing.

The material withstands the dropping-block test equally as well as fabriosupportcd vinyl or rubbera surfaced upholstry material. In fact, it is a complete equivalent for fabric-supported upholstry. Its support comes from the very strong scrim libers, and its wearability and exability is derived from the crimped nature of the fibers plus the strengthening which the impregnation with rubber brings about.

The impregnated fabrics not only are useful as upholstery and automotive seat coverings, they may be used for pocketbooks, belts, handbags, in shoes, and for luggage of various sorts.

The unimpregnated fabric has a felt-like appearance, possesses a high-tear strength, and can be handled in further manufacturing processes in the same manner as high-grade felts or woven fabrics.

The fabrics have good drape and flexibility, smooth surfaces, high ber density, and can be dyed and colored, and put to the normal use of felt. In addition, the unimpregnated fabrics may be employed in papermakers felts, printing press blankets, filter cloth, etc.

I claim:

1. The process of preparing a reinforced fabric which comprises mechanically interlocking at least one nonwoven brous web with a potentially heat-shrinkable reinforcing scrim, compressively heat shrinking the scrim and simultaneously crimping the threads and fibers of said scrim by passing the mechanically interlocked non-woven fibrous web and retractable reinforcing scrim together between the nip formed by a traveling endless belt having an elastic contractable surface and a smooth heated metal surface, to cause heat from the metal surface to shrink the scrim fibers and to cause the contractable surface to crimp the said scrim fibers whereby hinge points are created in the web, and superior crease resistance is imparted to the sheet.

2. The process of claim 1 wherein, subsequent to the compressive shrinking operation, the web is impregnated with an elastomeric material.

3. The process of claim 1 wherein, prior to the compressive shrinking operation, the web is conditioned by exposure to a water-vapor saturated atmosphere.

4. The process as dened in claim 1 wherein the said mechanical interlocking is secured by needling the nonwoven Web into the retractable scrim.

5. The process of preparing a reinforced fabric comprising mechanically interlocking at least one non-woven fibrous web with a potentially heat-shrinkable reinforcing scrim and subsequently heat shrinking the scrim and crowding the fibers of said scrim into a length less than their linear extent by passing the mechanically interlocked web between the nip formed by a traveling endless belt having an elastic contractable surface and a smooth heated metal surface.

References Cited UNITED STATES PATENTS 3,156,926 11/1964 Hoffman et al. 1618O 3,245,863 4/1966 Sonnichsen et a1. 161-72 3,191,257 6/1965 Smith 161-81 PHILIP DIER, Primary Examiner U.S. Cl. X.R. 

